data_global _chemical_name_mineral 'Forsterite' loop_ _publ_author_name 'Henderson C M B' 'Redfern S A T' 'Smith R I' 'Knight K S' 'Charnock J M' _journal_name_full 'American Mineralogist' _journal_volume 86 _journal_year 2001 _journal_page_first 1170 _journal_page_last 1187 _publ_section_title ; Composition and temperature dependence of cation ordering in Ni-Mg olivine solid solutions: A time-of-flight neutron powder diffraction and EXAFS study Sample: Mg80Ni20 at T = 300 C, on cooling ; _database_code_amcsd 0002721 _chemical_formula_sum '(Ni.4 Mg1.6) Si O4' _cell_length_a 4.75898 _cell_length_b 10.2340 _cell_length_c 5.98423 _cell_angle_alpha 90 _cell_angle_beta 90 _cell_angle_gamma 90 _cell_volume 291.452 _exptl_crystal_density_diffrn 3.520 _symmetry_space_group_name_H-M 'P b n m' loop_ _space_group_symop_operation_xyz 'x,y,z' 'x,y,1/2-z' '-x,-y,1/2+z' '1/2+x,1/2-y,1/2+z' '1/2-x,1/2+y,1/2-z' '1/2-x,1/2+y,z' '1/2+x,1/2-y,-z' '-x,-y,-z' loop_ _atom_site_label _atom_site_fract_x _atom_site_fract_y _atom_site_fract_z _atom_site_occupancy _atom_site_U_iso_or_equiv Ni1 0.00000 0.00000 0.00000 0.34900 0.00735 Mg1 0.00000 0.00000 0.00000 0.65100 0.00735 Ni2 0.99100 0.27750 0.25000 0.05100 0.00798 Mg2 0.99100 0.27750 0.25000 0.94900 0.00798 Si 0.42590 0.09370 0.25000 1.00000 0.00469 O1 0.76640 0.09260 0.25000 1.00000 0.00760 O2 0.22220 0.44740 0.25000 1.00000 0.00760 O3 0.27630 0.16250 0.03320 1.00000 0.00811